Solvent-free and room temperature visible light-induced C–H activation: CdS as a highly efficient photo-induced reusable nano-catalyst for the C–H functionalization cyclization of t-amines and C–C double and triple bonds

Abstract

Nano-sized CdS was successfully prepared, fully characterized and applied as a highly efficient reusable photocatalyst for the synthesis of pyrrolo[3,4-c]quinolone and pyrrolo[2,1-a]isoquinoline-8-carboxylate derivatives through a condensation reaction of N,N-dimethylanilines or alkyl 2-(3,4-dihydroisoquinolin-2(1H)-yl)acetates with maleimides via a C–H activation approach under benign and eco-friendly conditions at room temperature without using any solvent and oxidant under visible light irradiation. Besides, the prepared photocatalyst has been successfully applied for the condensation reaction of N,N-dimethylanilines with alkyl but-2-ynedioates or phenyl acetylenes for the synthesis of novel 1,2-dihydroquinoline-3,4-dicarboxylate and aryl-1,2-dihydroquinoline derivatives for the first time. Using this method, all favourable products were obtained in good yields and relatively short reaction times under benign conditions with the application of visible light irradiation, a renewable energy source. The catalyst was easily recovered and reused several times without any loss of its activity.